Determine the power status of a connected display with Bookworm Wayland

Last updated November 8, 2024 / By

If you want to check the status of your display, you can now use the 

wlr-randr

command.

Tested with Raspberry Pi OS Bookworm Wayland on a Raspberry Pi 4 (Nov 2024).

The output will be similar to

HDMI-A-1 "HJW HDMI TO USB 0x00000001 (HDMI-A-1)"
  Physical size: 700x390 mm
  Enabled: no
  Modes:
    1920x1080 px, 60.000000 Hz (preferred)

giving you a clear feedback with “Enabled:” if the monitor is on or off.

You will also see many other display modes/resolutions and you can grab the information that you like from the output file.

I wrote a Python test script parsing the output and checking the display status.

#!/usr/bin/python3

import subprocess

def is_display_enabled():
    try:
        # Run the wlr-randr command and capture its output
        command = "wlr-randr"
        output = subprocess.check_output(command, shell=True).decode('utf-8')

        # Check if any display has "Enabled: yes" in the output
        for line in output.splitlines():
            if 'Enabled:' in line:
                enabled_status = line.split(':')[1].strip()
                if enabled_status.lower() == 'yes':
                    return True
        return False  # If no display is enabled
    except subprocess.CalledProcessError:
        # Handle any errors that may occur
        return False

if is_display_enabled():
    print("A display is on.")
else:
    print("All displays are off.")

I am using it to let Home Assistant know if my display is on or off.

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